System of signaling.



No. 725,605. PATENTED APR. 14, 1903- N. TESLA. D SYSTEM OF SIGNALING.

APPLICATION FILED JULY 16-, 1900.

.H0 MODEL.

; UNITED STATES I PATENT OFFICE;

NIKoLA TESIJA, on NEW YORK, N,

SYSTEM oF SlG NA L lNG L SPECIFICATION forming part of Letters Patent No, 725,605, dated April 14, 1903.

Applicatitn filed July 16,1900. Serial No. 23,847. (No model.) l

' To all whom it may concern:

Be it known. that I, NIKO LA TESLA, a citizen of the United States,'r'esidingin theborough of Manhattan, in the city, county, and

State of New York, have invented certain new anduseful Improvements in Systemsiof Signaling, of which the followingis a specification,'reference being had to the drawings accompanying and forminga part of the same.

In certain systems for transmitting intelli gible messages or governing the movements and operations of distant automataelectrlcal impulses or disturbances produced by suitable apparatus are conveyed-.thro ugh the natural media to a distant receiving-circuit capable of responding to the impulses, and

therebyeffecting the control of other appliances. Generally a special device highly sensitive is connected'to the'receiving-circult, which in order to renderi it still more susceptible and to reduce the liability of its being affected by extraneous disturbances is carefully adjusted so as to be in tune with the transmitter. By a scientific designof the sending and receiving circuits and other apparatus and skilfu'l adjustment of the same these objects maybe in a measure attained;

but in long experience I have found that not! withstanding all constructive advantages and experimentalresources'this method is in,

many cases inadequate. Thus while Ih'ave succeeded in so operating selectively under certain favorable conditions morethan one hundred receivers in most-cases it is'practicable to rworl; successfully but a few, the

number rapidly diminishing as, either owing to'great distance or other causes, the energy available in the tuned circuits becomes smallerand the receivers necessarily more delicate. ,Evidently a circuit however well constructed-and adjusted to respond exclusively to vibrations of one period is apt to be affectlower ones. I very high frequ ency, the number of the effective harmonicsmay be large, and the receiver consequently easily disturbed by extraneous-influences to such an extent that when very shortwaves, such as these produced byfHertzian spark apparatus, are used 11ittlc advantage in'this respect is derived from tuning the circuits. It'being an im* perative requirementin most practical applications of such systemsof signaling or intelligence transmission 7 that the signals or messages should be exclusive or private, itis highly desirable to do away with the above limitations, especially in view of the fact, which I have observed, that the influence of powerful electricaldisturbances upon sensitive receivers extends, even on land, to distances of "many hundreds of miles,and consequently in accordance withv theory still farther on sea. To overcome these drawbacks and to enable a great'nu'mber of transmitting and receiving stations to be operated selectively and exclusively and withoutany danger of the signals or messages being disturbed,

intercepted, or interfered with in any way is the object-of my presentinventionQ Broadly stated, this invent on consists inv the combination of. meansforgenerati'ng and transmitting two ormore kinds orvclasses of disturbances or impulses of distinctive character with respect :to their efiect upona receiving-circuit ,and'a distant receiver which comprises two or more circuits-of different electrical character, or severally tuned, so as tobe responsive to the ,difierent kinds or classes of impulses'an'd which is dependent for operation upon the conjoint or resultant action of the two or more circuits or theseveral instrumentalities controlled or operated thereby. By employing only two kinds of vdisturbances or seriesof impulses. instead of one, as has heretofore been doneftooperate a receiver of this kind, I have found that safety against the disturbing influences of other sources isincreased to such an extent that I believe this number to be amply sulficient in most cases for rendering the ex-,

change of. signals {or messages reliable and exclusive; but in exceptional instances a greater number may be usedand a degree of safety against mutual and extraneous interference attained, such as is comparable to that afforded by a combination-lock, "The liability of a receiver being afiected by disturbances emanating from other sources, as well as that of the signals, or messages being received by instruments for which they are not intended, may, however, be'reduced not only by an increased number of the codperative disturbances or series of impulses, but also by a judicious choice of the same and the order in which they are made to act upon the receiver.

Evidently there are a great many ways of generating impulses or disturbances of any wave length, wave form, number or order of succession, or of any special character such as will be capable of fulfilling the requirements above stated, and there are also many ways in which such impulses or disturbances may be made to cooperate and to cause the receiver to be actuated, and inasmuch as the skill and practical knowledge in these novel fields can only be acquired by long experience the degree of safety and perfection attained will necessarily depend u pon the ability and resource of the expert who applies my invention; but in order to enable the same to be successfully practiced by any person possessed only of the more general knowledge and experiencein these branches I shall describe the simplest plan of carrying it out which is at present known to me.

For a better understanding of the subject reference is now made to the accompanying drawings, in which Figures 1 and 2 represent diagrammatically the apparatus and circuit connections employed at the sending and receiving stations, respectively; and Figs. 3, 4, and 5 modified means which may be employed in the prac: tical application of the invention.

In Fig. 1, S and S are two spirally-wound coils or conductors connected with their inner ends to elevated terminals D and D respectively, and with their outer ends to an earth-plate E. These two coils, conductors, or systems D S EJand D S E have difierent and suitably-chosen periods of'vibration, and, as pointed out in other patents relating to my system of energy and intelligence transmission, their lengths should be such that the points of maximum pressure developed therein coincide with the elevated terminals D D The two systems may have electrical oscillations impressed upon them in any desired manner, conveniently by energizing them through primaries P and P placed in proximity to them. Adjustable inductances L and L are preferably included in the primary circuits chiefly for the purpose of regulating the rates of the primary oscillations. In the drawings these primaries P and P surround the coils S S and are joined in series through the inductances L L", conductor F, condensers O and C brush-holders B and B and a toothed disk D, which is connected to the conductor F and, if desired, also to the ground-plate E, as shown, two independent primary circuits being thus formed.

The condensers C and O are of such capacity and the inductances L and L are so adjusted that each primary is in close resonance with its secondary system, as I have explained Q in other patents granted to me. The brush holders B and B are capable independently of angular and, if necessary, also of lateral adjustment, so that any desired order of succession or any diiference of time interval between the discharges occurring in the two primary circuits may be obtained. The condensers being energized from a suitable source S, preferably of high potential, and the disk D being rotated, its projections or teeth 12 13, coming at periodically-recurring intervals in very close proximity to or, as the case may be, in contact with conducting rods or brushes n n, cause the condensers to be discharged in rapid succession through their respective circuits. In this matter the two secondary systems D S E and D S E are set in vibration and oscillate freely, each at its proper rate, for a certain period of time at every discharge. The two vibrations are impressed upon the ground through the plate E and spread to a distance reaching the receivingstation, which has two similar circuits or systems e s d and e s (1 arranged and connected in the same manner and tuned to the systems at the sending-station, so that each responds exclusively to one of the two vibrations produced by the transmitting apparatus. The same rules of "adjustment are observed with respect to the receiving-oircuits,care being, furthermore, taken that the tuningis effected when all the apparatus is connected to the circuits and placed in position, as any change may more or less modify the vibration. Each of the receiving-coils s" and s is shunted .by a local circuit containing, respectively, sensitive devices a of, batteries b 12 adj ustable resistances r' 7*, and sensitive relays R R all joined in series, as shown. The precise connectionsand arrangements of the various receiving instruments are largely immaterial and may be varied in many ways. The sensitive devices a a may be any of the well-known devices of this kindas, for example, two conducting-term inals separated by a minute air-gap or a thin film of dielectric which is strained or weakened by abattery or other means to the point of breaking down and gives Way to the slightest disturbing influence. Its return to the normal sensitive state may be secured by momentarily interrupting the battery-circuit after each operation or otherwise. The relays R Rfhave armatures Z l, which are connected by a wire to and when attracted establish electrical contacts at c and 0 thus closing a circuit containing a battery b-', an adjustable resistance r and a relay R From the above description it will be readily seen that the relay R will be operated only when both contacts 0 and c are closed. The apparatus at the sending-station may be controlled in any suitable manner-as, for instance, by momentarily closing the circuit of the source S, two different electric vibrations being emitted simultaneously or in rapid succession, as may be-desired, at each closure of the circuit. lhe two'receiving-cirfcuits at the distant station, each tuned to respond to the vibrations produced by one of the elements of the transmitter, affect the sensitive'devices a and a and cause the relays R and R to be operated and contacts a and c to be closed, thus actuating the receiver or relay R which in turn establishes a contact 0 and brings into action a device a by means of a battery 01 included in a local circuit, as shown; but evidently if through any'extraneousdisturbance only one of the sage; but it the use of the systemis such that in such discharges.

this is necessary then the two station's-will be'similarly equipped and any'well-known means, which it is not thought necessary to illustrate here, may be resorted to for en'ablin g the apparatus at each station to be used in turn as transmitter and receiver. 111 like manner the operation-of a receiver, as R may be made dependent, instead of upontwo, upon more than two such transmitting 'sys tems or circuits, and thus any desired degree of exclusiveness or privacy and safety against extraneous disturbances-may be attained. The apparatus as illustrated in Figs. 1 and 2 permits, however, special results to be secured by the adjustment of the'order of succession of the discharge of the primarycircuits P and P 01 of the time interval between To illustrate, the action of the relays R B. may be regulated either by adjusting the weights of the levers Z Z or the strength of the batteries 1) b or the re si'stances 1" T or in other well-known ways,

so that when a certainorder of'successi'on or time interval betweenthe discharges of the prioperate the relay R but it will fail to pro 50 duce this result when the order of succession of or the time interval between the discharges in the primary circuits is another one. f By these or similar means additional safety against disturbances from other sources may be attained and, on the other hand, the possibility afforded of effecting the operation of signaling by varying the order of successionof the discharges of thetwo circuits. In-

' stead of closing and opening the circuit of the source S, as before indicated, for the purpose of sending distinct signals it may be convenient to merely alter the period of either of the transmitting-circuits arbitrarily, as-by varying the inductance ofthe primaries.

Obviously thereis no necessity for using;

transmitters with two or more distinct elements or circuits, as S and 8*, since a succession of waves orimpulse's of different characteristics maybe produced by an'iinstrument having but one suchcircuitu ,A few of the many ways which will readily suggest themselves to the expert who appliesmy invention are illustrated in Figs. 3, 4, and 5.

In Fig. 3a transmitting system e s d is partly shunted by a rotating wheel or disk D ,which may be similar to that illustrated in Fig.1 and which cuts out periodically a portion of the coil or conductor 8 or, if desired, bridges it "by an adjustable condenser O thusaltering the vibration of'the system es d at suitable intervals and causing two distinctkinds or classes of impulsesto be emitted in rapid insulating and conducting segments, a ciricu'i-t'p in'inductive relation to said system.

Again, in Fig. 5'three distinct vibrations are caused to be emitted'bya system c s (i this result being prod'ucedby inserting periodically a suitable number of turns of an induction-coil L in series with theoscillating system by means of a rotatingdisk B with-two proj ections p p and threerod's or' brushes n placed atan angle of one hundred and twenty degrees relatively'to e'ach 'o'ther; The three transmitting systems'oncircuits thu'sproduced may be energized'in the same'manner as those of Fig.1 or in any other convenient way. Corresponding toeach-of these'cascs the receiving-station may be' provided with two or three circuits i ii an analogous manner to that illustrated in Fig. 2,it being understood, of course, that the diiferent vibrations or disturbancesemittedby the sender follow in'such rapid succession upon each other-that they are practically simultaneous, so-far as the operation of such relays as R and R is concerned. Evidently, however, it is not necessary to employ two or more receiving-circuits; but a single circuit may be'used also at the receiving station constructed and ar: ranged like the transmitting circuits or systems illustrated in Figs. 3, 4, and 5, in which case the corresponding disks, asD D D ,'at

the sending will be driven in 'synchronismwith those at the receiving stationsas far as may be necessary to secure the desired result; but whatever the nature of the specific devices employed it will be seen that the f undamental idea in myinvention'is'the operation of a receiver by'the conjoint or resultant effect of two or more circuits 'cachtuned to respond exclusively to waves, impulses, for vibrations of a certain kind or class"produ ed either simultaneously or successivelyfby suitable transmitter.

Itwill be-seen' from a consideration of the nature of the method he reinbefore described that the invention is applicable not only in the special manner describedfin which the,

transmission of the impulses 'is 'eifect'ed through natural media, but for the transmission of energy for any purpose and whatever the medium through which the impulses are conveyed.

What I claim is- 1. In a system for the transmission of electrical energy, the combination with means for producing two or more distinctive kinds of disturbances or impulses, of receiving-circuits, each tuned to respond to the waves or impulses of one kind only, and a receiving device dependent for operation upon the conjoint action of the several receiving-circuits, as set forth.

2. In a system for the transmission of electrical impulses and the operation or control, of signaling or other apparatus thereby, the combination with a transmitter adapted to produce two or more distinctive kinds or classes of disturbances or impulses, of sensitive receiving-circuits, each tuned to respond to the impulses or disturbances of one kind or class only, and a receiving device dependent for operation upon the conjoint action of the sensitive circuits, as set forth.

3. In a system for the transmission of electrical impulses, and the operation or control of signaling, or other apparatus thereby, the combination with a transmitter adapted to produce two or more distinctive kinds or classes of disturbances or impulses, of sensitive circuits at the receiving point or station, each tuned to respond to the impulses or disturbances of one kind or class only, a local circuit arranged to be completed by the conjoint action of the sensitive circuits and a receiving device connected therewith, as set forth.

4. In a system for the transmission of electrical impulses, and the operation or control of signaling or other apparatus thereby, the combination with a transmitting apparatus adapted to produce two or more distinctive kinds of disturbances or impulses, of means for varying the time intervals of the emission of the impulses of the several kinds, sensitive circuits each tuned to respond to the impulses or disturbances of one kind only, and a receiving apparatus dependent for operation upon the conjoint action of the sensitive circuits, as set forth.

5. In a system, such as herein described, the combination with a transmitter adapted to produce a plurality of distinctive kinds of electrical disturbances or impulses, of a receiving apparatus comprising a plurality of circuits, a sensitive device and a relay included in each circuit, and each said circuit being tuned to respond to the impulses or disturbances of one kind only, and a receiving apparatus in a local circuit controlled by the relays and adapted to be completed by the conjoint action of all of said relays, as set forth.

6. In a system of the kind described, the combination with a transmitter adapted to produce two or more series of electrical oscillations or impulses of different frequencies,

of a receiving apparatus comprising a plurality of sensitive circuits each tuned to respond to the impulses of one of the series produced by the transmitter, and a signaling device dependent for its operation upon the 'conjoint action of said circuits, as set forth.

7. The combination with a plurality of transmitter elements, each adapted to pro duce a series of impulses or disturbances of a distinctive character, and means for controlling and adjusting the same, of a receiver having a plurality of sensitive circuits each tuned so as to be affected by one of the series of impulses only, and dependent for operation upon the conjoint action of all of said circuits, as set forth.

8. The combination with a transmitter adapted to produce series of electrical impulses or disturbances of distinctive character and in a given order of succession, of a receiving apparatus comprising tuned circuits responding to such impulses in a corresponding order, and dependent for operation upon the conjoint action of said elements, as set forth.

9. In a receiving apparatus, the combination with a plurality of sensitive circuits, severally turned to respond to Waves or impulses of adifierent kind or class, a receiving-circuit controlled by the sensitive circuits and a device connected with the receiving-circuits adapted to be operated when said circuit is completed by the conjoint action of two or more of the sensitive circuits, as set forth.

10. A system for the transmission of electrical energy, having in combination means ior producing and transmitting two or more impulses of different periodicities to form a signal in a predetermined order of succession, as set forth.

11. In a system for the transmission of electrical energy, the combination with a transmitting apparatus comprising one or more circuits, means for impressing therein oscillations or impulses of different character and a receiving apparatus comprising a plurality of circuits each tuned to respond to the impulses of one kind produced by the transmitter and a receiver dependent for operation upon the conjoint action of the receiving-circuits, as set forth.

12. In a system for the transmission of electrical energy, the combination with a transmitting apparatus comprising a transformer and means forimpressing upon the secondary element of the same oscillations or impulses of dilferent character, of a receiving apparatus comprising a plurality of circuits each tuned to the impulses of one kind emitted by the secondary of the transmitting transformer, and a receiver dependent for operation upon the conjoint action of the receiving-circuits, as set forth.

13. In a system for the transmission of electrical energy, the combination with a transmitting apparatus comprising a transformer and means for impressing upon the secondary elements of the same oscillations or impulses of difierent periodicities and in a given order of succession, of a receiving, apparatus comprising a plurality of circuits each tuned to 5 respond to the transmitted impulses of one period, and a receiver dependent for operation upon the conjoint action of the receivingcircuits, as set forth.

14. In a signaling system, the combination to of means for generating a series of electrical impulses of difierent periodicities, receivingcircuits of differing electrical periods of vibration, and an indicating mechanism operated to give an intelligible indication only I5 when currents are induced in the receivingcircnits in a predetermined order, as set forth.

15. In a system for the transmission of energy, the combination of two or more circuits termined order, of a receiving instrument responsive to said oscillations and dependent for operation upon the action thereof-in a corresponding order, as set-forth.

, NIKOLA TESLA. Witnesses:

J OHN 0. KERR, RICHARD S. DONOVAN. 

